Table Of ContentDurability of
Concrete Structures
Durability of
Concrete Structures
Investigation, repair, protection
Edited by
GEOFF MAYS
School of Mechanical, Materials and Civil Engineering
RMCS (Cranfield)
E & FN SPON
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This edition published in the Taylor & Francis e-Library, 2003.
First edition 1992
© 1992 E & FN Spon
ISBN 0-203-47347-7 Master e-book ISBN
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ISBN 0 419 15620 8 0 442 314272 (USA)
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Contents
Preface xi
Biographic summary of contributors xii
PART ONE THEORIES AND SOLUTIONS
1 The behaviour of concrete 3
G.C.Mays
1.1 Historical development of concrete 3
1.2 Concrete—the material 4
1.3 Mechanisms and causes of failure 5
1.4 Intrinsic deterioration of concrete 6
1.5 Environmental attack 7
1.6 Prevention and repair 8
1.7 The extent of the problem 9
2 Deterioration mechanisms 10
T.P.Lees
2.1 Introduction 10
2.1.1 Cement 11
2.1.2 Hydration of cement 12
2.1.3 Physical structure of cement paste 13
2.1.4 Simplified model of concrete 14
2.2 Deterioration of concrete 15
2.2.1 Early deterioration 15
2.2.2 Deterioration arising from concrete ingredients 21
2.2.3 Concrete deterioration caused by external agents 23
2.2.4 External effects leading to corrosion
of reinforcement 33
3 Structural investigations 37
A.F.Baker
3.1 Introduction 37
v
vi Contents
3.2 Planning an investigation 38
3.2.1 Preliminary considerations 38
3.3 Test and inspection techniques 41
3.3.1 In situ sampling and testing 41
3.3.2 Determination of structural integrity 44
3.3.3 Determination of concrete quality 51
3.3.4 Steel serviceability and condition 62
3.3.5 Laboratory testing and sample analysis 65
3.3.6 Visual examination of concrete 66
3.3.7 Physical testing of concrete to determine quality 67
3.3.8 Chemical analysis of concrete 70
3.3.9 Petrographic examination of concrete 72
3.4 Interpretation of condition surveys 76
4 Repair materials and techniques 82
L.J.Tabor
4.1 Introduction 82
4.2 Materials for concrete repair 84
4.2.1 Sources 84
4.2.2 The specialist formulator 84
4.2.3 Replacement materials—the choice 85
4.2.4 Resin mortars 86
4.2.5 Cementitious repair packages: examining the systems 89
4.2.6 Crack repairs 101
4.2.7 Superfluid microconcretes 103
4.3 Repair techniques 105
4.3.1 Removal of defective concrete 105
4.3.2 Cleaning the steel reinforcement 106
4.3.3 Protecting the steel reinforcement 107
4.3.4 Using a bond coat 108
4.3.5 Mixing mortars and concretes 110
4.3.6 Placing 113
4.3.7 Crack injection 119
4.3.8 Sprayed concrete 125
4.4 Safety 127
5 Protection 130
A. Cathodic protection 130
K.G.C.Berkeley
5.1 Introduction to cathodic protection 130
5.1.1 The background to corrosion attack 130
5.1.2 Electrochemical corrosion 131
Contents vii
5.2 How cathodic protection works 134
5.3 Associated problems 138
5.4 Practical applications of cathodic protection 140
5.5 Concluding remarks 145
B. Surface treatments
J.G.Keer
5.6 Introduction to surface treatments 146
5.7 Types of surface treatment 146
5.7.1 Coatings and sealers 147
5.7.2 Pore-lining treatments 149
5.7.3 Pore-blocking treatments 151
5.7.4 Renderings 152
5.8 Application of surface treatments 152
5.9 Surface treatments to control carbonation 153
5.10 Surface treatments to control moisture or chloride ingress 157
5.11 Concluding remarks 163
6.Conclusions 166
G.C.Mays
6.1 The future 166
6.2 Maintenance policies 167
PART TWO CASE STUDIES
7 High-rise buildings 173
C.Stroud and P.Gardner
7.1 Introduction 173
7.2 Five year Tall Block Inspection Programme 174
7.2.1 Evolution of the inspection programme 174
7.2.2 The client brief for the tall block inspection 174
7.2.3 Methodology 175
7.2.4 Development of the tall block inspection brief 176
7.2.5 Typical structural defects identified by the
inspection programme 177
7.3 High-rise repair strategies 177
7.3.1 Public safety (emergency) works 177
7.3.2 Holding repairs 178
7.3.3 Full refurbishment 179
7.3.4 Demolition 180
7.3.5 Sale 180
7.4 Repair and maintenance strategies 180
7.4.1 Preventative maintenance 180
7.4.2 Criteria for strategies 181
viii Contents
7.5 Case studies 182
7.5.1 Thomas North Terrace 182
7.5.2 Herbert Willig House 185
7.6 Concluding remarks 186
8.Highway bridges 188
K.J.Boam
8.1 Introduction 188
8.2 Scale of the problem 188
8.2.1 Bridge decks 189
8.2.2 Bridge sub-structures 191
8.2.3 Retaining walls 192
8.3 Diagnosis 192
8.4 Options for repair 194
8.4.1 Do nothing 195
8.4.2 Reduce corrosion rate 195
8.4.3 Repair visual defects 195
8.4.4 Carry out major repairs 196
8.4.5 Apply cathodic protection 198
8.4.6 Replace affected elements 200
8.5 Monitoring of repairs 201
8.6 Avoiding future problems 206
9 Railway structures 206
J.F.Dixon
9.1 Introduction 206
9.2 Steel reinforcement corrosion 207
9.2.1 Chloride problems 207
9.2.2 Carbonation 219
9.3 Concrete deterioration 220
9.3.1 Frost attack 220
9.3.2 Alkali-silica reaction 221
9.3.3 Surface appearance 222
9.4 The future 224
10 Concrete pavements 226
G.D.S.Northcott
10.1 Introduction 226
10.2 Defects 227
10.2.1 Investigation 227
10.2.2 Types of defect 228
Contents ix
10.2.3 Joint defects 228
10.2.4 Surface defects 230
10.2.5 Structural defects 232
10.2.6 Material defects 232
10.3 Design faults and remedies 234
10.3.1 Joint seals 234
10.3.2 Deep spalling at joints 235
10.3.3 Longitudinal cracking 236
10.3.4 Cracks at manholes and gallies 236
10.4 Construction faults and remedies 237
10.4.1 Joint defects 237
10.4.2 Surface defects 240
10.4.3 Structural defects 241
10.5 Maintenance faults and remedies 242
10.5.1 Joint sealing 243
10.5.2 Joint arris repairs 244
10.6 Repair materials 246
10.7 Overlaying and strengthening 246
11 Marine structures 248
M.B.Leeming
11.1 Introduction 248
11.2 The need for repairs 249
11.2.1 The underwater zone 249
11.2.2 Above water 249
11.2.3 The repairing of cracks 250
11.2.4 The durability of repairs 250
11.3 Repairs to deteriorated concrete 252
11.3.1 Spalling and reinforcement corrosion 252
11.3.2 Repairing cracks 253
11.3.3 Repair of construction faults 253
11.4 Repairs necessitated by damage to offshore structures 254
11.4.1 Shipping damage 254
11.4.2 Damage due to dropped objects 254
11.4.3 Fire damage 254
11.4.4 Gouges and abrasion 255
11.5 Case studies of repair methods 255
11.5.1 Shipping damage to the leg of an
offshore structure 255
11.5.2 Punching shear failure to a caisson roof 255
11.5.3 Gouges in concrete cell tops and caisson walls 258
11.5.4 Damage to piles, jetties and other coastal
structures 258
